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Subject[PATCH 06/19] btrfs: align dev extent allocation to zone boundary
Date
In HMZONED mode, align the device extents to zone boundaries so that a zone
reset affects only the device extent and does not change the state of
blocks in the neighbor device extents. Also, check that a region allocation
is always over empty same-type zones.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
fs/btrfs/extent-tree.c | 6 +++
fs/btrfs/volumes.c | 100 +++++++++++++++++++++++++++++++++++++++--
2 files changed, 103 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1aee51a9f3bf..363db58f56b8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -9884,6 +9884,12 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
min_free = div64_u64(min_free, dev_min);
}

+ /* We cannot allocate size less than zone_size anyway */
+ if (index == BTRFS_RAID_DUP)
+ min_free = max_t(u64, min_free, 2 * fs_info->zone_size);
+ else
+ min_free = max_t(u64, min_free, fs_info->zone_size);
+
mutex_lock(&fs_info->chunk_mutex);
list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
u64 dev_offset;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b6f367d19dc9..c1ed3b6e3cfd 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1737,6 +1737,46 @@ static bool contains_pending_extent(struct btrfs_device *device, u64 *start,
return false;
}

+static u64 dev_zone_align(struct btrfs_device *device, u64 pos)
+{
+ if (device->zone_size)
+ return ALIGN(pos, device->zone_size);
+ return pos;
+}
+
+/*
+ * is_allocatable_region - check if spcecifeid region is suitable for allocation
+ * @device: the device to allocate a region
+ * @pos: the position of the region
+ * @num_bytes: the size of the region
+ *
+ * In non-ZONED device, anywhere is suitable for allocation. In ZONED
+ * device, check if the region is not on non-empty zones. Also, check if
+ * all zones in the region have the same zone type.
+ */
+static bool is_allocatable_region(struct btrfs_device *device, u64 pos,
+ u64 num_bytes)
+{
+ int is_sequential;
+
+ if (device->zone_size == 0)
+ return true;
+
+ WARN_ON(!IS_ALIGNED(pos, device->zone_size));
+ WARN_ON(!IS_ALIGNED(num_bytes, device->zone_size));
+
+ is_sequential = btrfs_dev_is_sequential(device, pos);
+
+ while (num_bytes > 0) {
+ if (!btrfs_dev_is_empty_zone(device, pos) ||
+ (is_sequential != btrfs_dev_is_sequential(device, pos)))
+ return false;
+ pos += device->zone_size;
+ num_bytes -= device->zone_size;
+ }
+
+ return true;
+}

/*
* find_free_dev_extent_start - find free space in the specified device
@@ -1779,9 +1819,14 @@ int find_free_dev_extent_start(struct btrfs_device *device, u64 num_bytes,
/*
* We don't want to overwrite the superblock on the drive nor any area
* used by the boot loader (grub for example), so we make sure to start
- * at an offset of at least 1MB.
+ * at an offset of at least 1MB on a regular disk. For a zoned block
+ * device, skip the first zone of the device entirely.
*/
- search_start = max_t(u64, search_start, SZ_1M);
+ if (device->zone_size)
+ search_start = max_t(u64, dev_zone_align(device, search_start),
+ device->zone_size);
+ else
+ search_start = max_t(u64, search_start, SZ_1M);

path = btrfs_alloc_path();
if (!path)
@@ -1846,12 +1891,22 @@ int find_free_dev_extent_start(struct btrfs_device *device, u64 num_bytes,
*/
if (contains_pending_extent(device, &search_start,
hole_size)) {
+ search_start = dev_zone_align(device,
+ search_start);
if (key.offset >= search_start)
hole_size = key.offset - search_start;
else
hole_size = 0;
}

+ if (!is_allocatable_region(device, search_start,
+ num_bytes)) {
+ search_start = dev_zone_align(device,
+ search_start+1);
+ btrfs_release_path(path);
+ goto again;
+ }
+
if (hole_size > max_hole_size) {
max_hole_start = search_start;
max_hole_size = hole_size;
@@ -1876,7 +1931,7 @@ int find_free_dev_extent_start(struct btrfs_device *device, u64 num_bytes,
extent_end = key.offset + btrfs_dev_extent_length(l,
dev_extent);
if (extent_end > search_start)
- search_start = extent_end;
+ search_start = dev_zone_align(device, extent_end);
next:
path->slots[0]++;
cond_resched();
@@ -1891,6 +1946,14 @@ int find_free_dev_extent_start(struct btrfs_device *device, u64 num_bytes,
hole_size = search_end - search_start;

if (contains_pending_extent(device, &search_start, hole_size)) {
+ search_start = dev_zone_align(device,
+ search_start);
+ btrfs_release_path(path);
+ goto again;
+ }
+
+ if (!is_allocatable_region(device, search_start, num_bytes)) {
+ search_start = dev_zone_align(device, search_start+1);
btrfs_release_path(path);
goto again;
}
@@ -5177,6 +5240,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
int i;
int j;
int index;
+ int hmzoned = btrfs_fs_incompat(info, HMZONED);

BUG_ON(!alloc_profile_is_valid(type, 0));

@@ -5221,10 +5285,20 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
BUG();
}

+ if (hmzoned) {
+ max_stripe_size = info->zone_size;
+ max_chunk_size = round_down(max_chunk_size, info->zone_size);
+ }
+
/* We don't want a chunk larger than 10% of writable space */
max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1),
max_chunk_size);

+ if (hmzoned)
+ max_chunk_size = max(round_down(max_chunk_size,
+ info->zone_size),
+ info->zone_size);
+
devices_info = kcalloc(fs_devices->rw_devices, sizeof(*devices_info),
GFP_NOFS);
if (!devices_info)
@@ -5259,6 +5333,9 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
if (total_avail == 0)
continue;

+ if (hmzoned && total_avail < max_stripe_size * dev_stripes)
+ continue;
+
ret = find_free_dev_extent(device,
max_stripe_size * dev_stripes,
&dev_offset, &max_avail);
@@ -5277,6 +5354,9 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
continue;
}

+ if (hmzoned && max_avail < max_stripe_size * dev_stripes)
+ continue;
+
if (ndevs == fs_devices->rw_devices) {
WARN(1, "%s: found more than %llu devices\n",
__func__, fs_devices->rw_devices);
@@ -5310,6 +5390,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,

ndevs = min(ndevs, devs_max);

+again:
/*
* The primary goal is to maximize the number of stripes, so use as
* many devices as possible, even if the stripes are not maximum sized.
@@ -5333,6 +5414,17 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
* we try to reduce stripe_size.
*/
if (stripe_size * data_stripes > max_chunk_size) {
+ if (hmzoned) {
+ /*
+ * stripe_size is fixed in HMZONED. Reduce ndevs
+ * instead.
+ */
+ WARN_ON(nparity != 0);
+ ndevs = div_u64(max_chunk_size * ncopies,
+ stripe_size * dev_stripes);
+ goto again;
+ }
+
/*
* Reduce stripe_size, round it up to a 16MB boundary again and
* then use it, unless it ends up being even bigger than the
@@ -5346,6 +5438,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
/* align to BTRFS_STRIPE_LEN */
stripe_size = round_down(stripe_size, BTRFS_STRIPE_LEN);

+ WARN_ON(hmzoned && stripe_size != info->zone_size);
+
map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
if (!map) {
ret = -ENOMEM;
--
2.21.0
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